Towards dealing with commonly occurring requirements engineering process issues during software development outsourcing

Due to specific advantages, the volume of Software Development Outsourcing (SDO) is rapidly increasing. Because of challenges arising from the Requirements Engineering (RE) process, the anticipated benefits of SDO are not achieved in case of several projects. The objective of this research work is to recommend RE practices for addressing the commonly arising RE process issues in the case of SDO. For this reason, a thorough literature review has been undertaken, as well as two questionnaire surveys have been performed with skilled SDO industry practitioners. The surveys have been done by utilizing semi-supervised style and employing Convenience Sampling method. The 50 percent rule and a four-point Likert Scale have also been used to determine the advantages of RE practices for dealing with the issues. A comprehensive list of 147 RE practices has been extracted by conducting a Focus Group session. Furthermore, the 147 RE practices have been ranked by applying Numerical Assignment and Hundred Dollar Techniques during two Focus Group sessions. The detection and adaptation of RE practices aids in enhancing the SDO RE process, evading SDO failures, and achieving the associated SDO advantages.


Introduction
Information Technology Outsourcing (ITO) is the subcontracting of particular services or the use of external resources to undertake IT functions [1]. The volume of ITO is steadily growing. The IT services outsourcing business was of worth $520.74 billion in 2019 and is expected to grow to $937.67 billion by 2027 [2].
Software Development Outsourcing (SDO) is a sort of ITO in which a customer contracts out some or all the software development operations to the vendor (s) [3][4][5][6]. For both advanced and developing countries, SDO generates a win-win state [7]. Software development projects are being outsourced to India, Russia, and China by European companies [8]. SDO

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PLOS ONE | https://doi.org/10.1371/journal.pone.0269607 July 14, 2022 1 / 32 a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 model has been developed for generating and choosing requirements for a software release [35]. In another study [36], knowledge transfer and reuse in the global RE perspective are also examined. Distance between partners and cultural differences have an impact on knowledge exchange. Improper reuse in RE is a result of mistrust and protectionism. The findings of an exploratory investigation on the role and relevance of the human moderator during dispersed RE, have also been presented [37].
The 43 most common RE process issues in the SDO scenario have been identified, classified, and prioritized based on their frequency of recurrence [38]. The 25 elements that can influence the offshore SDO RE process have also been discovered and verified [39]. With efficiency and cost reduction in mind, Ahmed and Abdulrahman have investigated the impact of localized decisions, about requirements, on software customization in the DSD scenario [40]. The RCM process for dispersed agile software development has been streamlined using a methodology and a tool [41]. Another study [42] presents 15 issues for quality requirements the in the case of huge DSD agile projects, as well as 13 processes and 9 strategies for dealing with the challenges. In the context of GSD, a well-ordered domain ontology has been recommended to aid the RCM process [43]. For the GSD scenario, the 30 RCM problems have been explored and classified [44]. The 23 elements that lead to an effective RCM for GSD, have been uncovered [45]. In another research work [46], a three-stage technique has been presented to aid the RCM process in the GSD scenario. The elements that facilitate the implementation of appropriate requirements in the GSD scenario, have been discovered and examined [47]. Two frameworks have been suggested and validated to study the significance of project management exclusively for RE and then RCM procedures in the context of GSD [48]. The 218 risks linked with the RE process in GSD scenario, as well as 146 measures to mitigate those risks, have been outlined [49]. A paradigm has been proposed to investigate the impact of geographical, intercultural, and spatial disparities on communication during RCM process in the GSD scenario [50]. Thirteen strategies have been discovered to support efficient communication for requirements elicitation in the context of GSD projects [51]. In GSD scenario, RCM obstacles have been discovered, confirmed, and quantified [52]. A methodology has been designed to evaluate GSD companies' preparedness for the RCM process in GSD scenario [53].
A two-phase approach for prioritising requirements in the GSD environment, has been presented depending on three criteria: weight, vote, and priority of partners [54]. A model has been created and tested to investigate the impact of fluctuating requirements on the sustainability of GSD initiatives [55]. Based on company scale and location, the success elements that are necessary for successful communication across the requirements elicitation in the GSD scenario have been examined [56]. A mechanism for specifying and validating requirements has been established by generating a requirements graph, particularly in GSD scenario [57]. A block-chain dependent approach has been presented to deal with the requirements discrepancies in GSD context [58]. With regard to business function, scale, and experts' ability, the 20 obstacles in the context of GSD RE scenario have been identified and confirmed [59]. The 15 problems for RCM in the offshore SDO scenario have been discovered [60]. The 14 problems for reusing requirements in the case of huge agile DSD projects, as well as 10 approaches to solve those problems have been recommended [61]. Focusing on 32 communication problems and 28 RE practices, a paradigm has been presented to tackle communication-related problems for the RE process in GSD scenario [62].
Thus, an examination of recent research reveals the fact that studies just partly resolve the SDO RE issues or partly present the RE practices to tackle SDO RE issues. To our knowledge, no research has ever presented a complete list of RE practices for dealing with the SDO RE process issues. As a result, the focus of this study is to establish an exhaustive list of RE practices to tackle the most prevalent SDO RE process issues that lead to SDO failures.

Research methodology
The committee for candidature defence has authorized this research work, which is part of my PhD study. This research's only human-associated subject matter is questionnaire surveys. The verbal agreement of prospective respondents or their corresponding organizations was requested prior to performing the surveys. In this study, no private data has been disclosed or examined in any way. The replies have been stated in a collective way. Individuals' and organizations' anonymousness and secrecy have been absolutely secured in this way.
To achieve research objectives, employed research methods are: Systematic Literature Review (SLR), questionnaire survey, 50% rule and focus group session. Fig 1 depicts

Systematic literature review
The objective of a SLR is to find, examine, and synthesize all available research on a particular research question, subject, or area of focus [63]. Barbara Kitchenham's technique [64] has been used to conduct the SLR in this study like the previous studies [65,66].

Questionnaire surveys
Both questionnaire surveys used in this study have been done utilising a semi-supervised technique, in which the survey's purpose, questionnaire structure, and numerous questions about the questionnaire are made explicit to respondents prior to survey [67]. Semi-supervised techniques have been employed in this study, either via head-on encounters with participants or via use of the Computer-Assisted Telephone Interviewing (CATI) methodology [68].
During the first survey, some questionnaires were provided and filled out at face-to-face meetings, while others were sent through emails. The Drop-Off/Pick-Up approach [69] was used for the second questionnaire survey.

The 50% rule
The 50 percent rule states that a viewpoint is considered if at least 50 percent of those polled agree with it. The analogous guideline has been applied in other investigations as well [70][71][72].

Focus group session
Focus groups are used to collect information about a certain topic chosen by the investigator. Focus groups are meticulously designed debates that allow participants to obtain personal insight into a certain study topic [73]. Focus groups have been used in numerous investigations [74,75].

First questionnaire survey
The survey research approach has been used to gather information on significant RE practices for SDO. The first questionnaire survey of the research work is based on Sommerville and Sawyer's 49 RE practices [22] for six major areas of the RE process: elicitation of requirements, evaluating and negotiating requirements, requirements description, modelling requirements, validating requirements, and maintaining requirements. The survey research approach is seen

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Addressing RE issues for software development outsourcing to be a good way to collect both qualitative and quantitative data [76]. Like Wohlin and Aurum [77], this survey was designed and conducted using the guidelines described in research [78].
A cross-sectional investigation was conducted for this survey. SDO practitioners received 130 surveys in total. Seventy (70) questionnaires were delivered and filled out at face-to-face meetings, while Sixty (60) questions were distributed and filled out over emails. The survey was carried out using either a semi-supervised approach [67], in which respondents were directed during face-to-face sessions, or the CATI technique [79]. In research, the CATI approach is commonly used [80][81][82].
The term "significant" refers to something that is "important enough to make an impact" [83, 84], therefore, significant RE practices means the RE practices which effect RE process.

Second questionnaire survey
The survey was designed and conducted using the guidelines described in research [78]. A cross-sectional investigation was conducted for this survey. The Drop-off/Pick-up approach was used to distribute 200 questionnaires. Various studies employed Drop-off/Pick-up approach [85,86]. The survey was carried out using a semi-supervised method [67]. The survey's goals, professionals' assumptions, questionnaire style, and respondents' questions were all clarified using the CATI approach [79].

Results and discussion
This section summarises the findings of the research analyses by focusing on the three phases outlined in the section of research methodology. The procedure is depicted in  To eliminate bias, two other investigators have been engaged throughout the process, and each phase has been concluded after reaching an agreement.
After a rigorous review and screening procedure, 117 studies were chosen for extracting data.
4.1.2. The RE practices to tackle SDO RE process issues. The 90 RE practices have been discovered, after a thorough examination of 117 studies, that can be applied to tackle the RE process issues in SDO scenario. The 90 RE practices denoted by the initials REPR 1 , REPR 2 , REPR 3 ,. . ., REPR 90 are as follows: REPR 1 = Putting in place the necessary infrastructure to support communication and guaranteeing that it is operational [87]; REPR 2 = Promoting synchronous communication using chat rooms, phone conversations, and videoconferencing [87]; REPR 3 = Adjusting to and comprehending various stakeholders' cultures [87], means being familiar with a culture's customs, values, ethos, and local language [5]; REPR 4 = Choosing and utilizing a standardized communication language [88]; REPR 5 = Concentrating on communication language improvement, such as English language classes [87,89,90]; REPR 6 = Employing cultural liaisons [87,89,91] or intermediaries (people who are conversant with customer and vendor cultures) [92]; REPR 7 = Creating a 'proximity training center' in a time zone that is the same or somewhat different from the client's zone [93]; REPR 8 = Attempting to identify natural overlaps in work time [94]; REPR 9 = Evaluating a person's capacity to work 'around the clock' [94]; REPR 10 = Time-shifting (adjusting one's working time to coincide with the work time of others) to attain time zone closeness, a variety of approaches for this purpose, are: i. Flextime (functioning on a flexible schedule to allow for overlapping).
ii. Overtime (functioning for additional time for overlapping).
iii. Telework (functioning for elastic schedules from home for overlapping). iv. Long working days (allowing for work time overlapping at the beginning or finish of the day).
v. Unrestricted working hours (employees decide their own operating time for overlapping and there are no standard work hours) [95]; REPR 11 = Providing electronic message "drop in", remote phoning, and artefact distribution capabilities to distant practitioners' rooms [96]; REPR 12 = Enabling professional integration from the outset of the project, such as by holding face-to-face kick-off meetings to create personal interactions [21,97]; REPR 13 = Organizing regular visits to isolated locations in order to foster trust [18,98,99]; REPR 14 = Encouraging direct contact amongst stakeholders [100]; REPR 15 = Assuring that stakeholders are introduced to each other from the start of the project [101]; REPR 16 = Facilitating interaction in the client's original tongue [5]; REPR 17 = Advising on the usage of groupware tools [99]; REPR 18 = Attempting to convince stakeholders that disclosing concerns or sharing information would have beneficial repercussions rather than adverse effects [94]; REPR 19 = Organizing video or teleconferences on day-to-day, weekly, semi-monthly, or monthly basis such that no or a few awkward hours exist for all the partners [98]; REPR 20 = Organizing requirements engineering sessions by: i. Using a human moderator and a rich communication medium that allows data, audios, and videos to be integrated.
ii. Making and sticking to an agenda.
iii. Identifying appropriate participants and notifying them on time to participate in requirements engineering sessions.
iv. Exchanging of reference materials in a timely manner to allow participants ample time to view the essential content.
v. Giving attendees of requirements sessions access to resources (like emails, relevant papers, work artefacts, and so on) containing information on the requirements [21]; REPR 21 = Setting up assertive governance at the project manager and team leader levels [102]; REPR 22 = Keeping track of the directives in a certain order [102]; REPR 23 = Personal and group obligations must be clearly stated and agreed upon [102]; REPR 24 = Getting obviously defined and grasped requirements engineering processes [102]; REPR 25 = Utilizing email as a communication verification tool because it preserves a written copy of contact [21,89,96]; REPR 26 = Getting agreements in writing and adequately documented [103]; REPR 27 = Creating an organizational structure with clear communication roles [91]; REPR 28 = At the various levels of team, project, and management; creating peer-to-peer connectivity across remote locations [91]; REPR 29 = Partly orchestrating inter-organizational procedures [91]; REPR 30 = Providing open channels of communication amongst stakeholders with clearly defined responsibilities [91]; REPR 31 = Assessing and communicating development on jointly approved artefacts on a regular basis [91]; REPR 32 = Making use of an awareness support system to manage requirements, all partners ought to be able to obtain the following details: i. Specifications, justifications, and priorities of various requirements.
ii. Requirements dependencies, as well as design, code, and testing dependencies.
iii. Duties of every member of the team in relation to specific requirement(s) and contact particulars like email address and phone number.
iv. The people who took initiatives for the requirements.
v. Issues relating to requirements, issues' activators, state of issues' resolution, and judgments made because of issues.
vi. Dates, times, and venues of the meetings, as well as the present stakeholders, debated issues and judgments done.
vii. Demands for change, change demand activators, state of every change demand, personnel engaged in making judgments, and judgments made [104]; REPR 33 = Retaining senior professionals on the team and persuading those professionals to bridge the knowledge gap [105]; REPR 34 = Putting in place a centralized communication system [105]; REPR 35 = After each meeting, making a report of the proceedings. Any member of the team or moderator ought to outline which issues were presented at the meeting, what decisions were taken about every issue, still open issues, who is responsible for gathering more data, and whose guidance should be solicited in the event of each issue [106]; REPR 36 = To use a Requirements Management System (to regulate and follow changes) that has the succeeding characteristics: i. Searching a list of requirements, extracting individual requirements, and organizing requirements according to certain criteria.
ii. Administration of the requirements modification process, assistance for requirements traceability, and development of various forms of requirements reporting.
iii. Acceptance of external documents via an interface.
iv. Managing several versions of requirements.
v. Aid for carrying out various forms of analyses (e.g., impact analysis, knowing whether a requirement is orphan, status tracking).

vi. Limiting access and editing privileges to the list of requirements [29];
REPR 37 = Notifying the pertinent partner regarding the change in requirements by: i. Communication technologies such as telephone, emails, and the internet.
ii. Using the system to send out automated notifications [107]; REPR 38 = In the event that there are a large number of partners: i. Designating a person (communication channel) out of each organizational unit or group of requirements sources to collect requirements from that unit or group. The requirements are then transferred to an expert via communication channels, where they might be combined [108].
ii. Obtaining unanimity on requirements employing group elicitation approaches like Brainstorming, JAD, Focus groups, and requirements Workshops [25].
iii. Generating a consolidated requirements document that includes all of the requirements [108]; REPR 39 = Adopting the following steps to address cultural challenges: i. (REPR 6 ) Employing cultural liaisons [87,89,91] or intermediaries (people who are conversant with customer and vendor cultures) [92].
ii. Advising members of the team to tour other partners' sites [109].
vi. Introducing a 'Negotiated Culture,' a negotiated culture created to respect all partners' cultural standards [103].
vii. Identifying persons with expertise and familiarity with the customer's culture to support for requirements discussion and definition [89].
x. The project manager or/and experienced team members planning and supervision of all the efforts that are carried out to cope with cultural differences [109]; REPR 40 = Presenting the Equality Model (EM) for all partners, in which all partners are treated equally and can discuss each other's preferences, religion, and social traditions. They can also exchange knowledge and make recommendations based on others' perspectives and roles [110]; REPR 41 = Defining the procedures, techniques, and policies that must be followed [111]; REPR 42 = Knowledge exchange [111]; REPR 43 = Observance of common hopes [111]; REPR 44 = Possessing technological, managerial, and personnel capabilities for satisfying quality standards & meeting deadlines [5]; REPR 45 = To inspire non-fluent or less confident partners to participate in the discourse, begin with an informal dialogue [112]; REPR 46 = Making use of translation facilities: i. Utilizing human interpreter [112,113].
ii. Utilizing real-time machine conversion facilities [113]; REPR 47 = Utilizing scales to calculate the mean time it takes for hopes to be met. For example, providing a feature that determines the average time it takes a person or team to react to an email. If the mean time to respond is three days, the sender may anticipate receiving a response within three days [114]; REPR 48 = Developing and utilizing a vocabulary and notations for requirements description [88]; REPR 49 = Vendor managers can take the following steps to establish collaboration: i. Establishing team members' roles and tasks, as well as constructing Organizational Charts that show their roles and obligations [115].
ii. Obtaining and administering the appropriate human resources using Resource Calendar [115].
iv. (REPR 28 ) At the various levels of team, project, and management; creating peer-to-peer connectivity across remote locations [91].
vi. (REPR 30 ) Providing open channels of communication amongst stakeholders with clearly defined responsibilities [91].
vii. (REPR 31 ) Assessing and communicating development on jointly approved artefacts on a regular basis [91]; REPR 50 = Achieving partners' agreement on meeting attendance terms and conditions, as well as fulfilling timelines and obligations [116]; REPR 51 = Identifying each team member's function and suggesting who might interact with whom [16,117]; REPR 52 = In terms of decisions, keep in constant contact with customers by organizing: i. Meetings in person.
ii. Video conferencing [16]; REPR 53 = Selecting a teammate that works beyond the typical business hours and responds to questions [118]; REPR 54 = Educating on in what manner to: i. Make use of the available tools.
ii. Interact efficiently in a situation where partners are scattered at remote sites [18]; REPR 55 = Giving prospective team members training about how to use relevant procedures, as well as associated tools and technology [119]; REPR 56 = Performing six general steps for RE, in absence of any standard RE process [20,120], which are: i) Requirements Elicitation, ii) Requirements Analysis & Negotiations, iii) Specifying Requirements, iv) System Modeling, v) Requirements Validation, and vi) Requirements Management [13,22,121]; REPR 57 = Adopting procedures that have been discussed and agreed upon [97]; REPR 58 = Utilizing tools which can connect with one another [107]; REPR 59 = Utilizing the ISO/IEC TR 24766:2009 framework and related data, for evaluating the functionalities of RE tools [122,123]; REPR 60 = Nominating a practitioner as requirements engineer or system analyst who possesses: i. Domain knowledge or is ready to understand domain and sophisticated elicitation procedures [124].
ii. Capabilities for working in the global context, with remote teams and people from other cultures [124].
iii. Ability to settle problems and operate in unclear and uncertain conditions [124].
iv. Autonomy (by employing access privileges, a peer sends data to others while simultaneously imposing limits, such as not providing data to specific peers) provision.
v. Intermittency (removal of a peer as a result of network disconnect, which can be purposeful or unintentional) detection [141]; REPR 83 = Taking into account Hofstede's cultural dimensions, for assisting managers in identifying individual and group conduct [109], which are: i. The distance between the power sources.
ii. Collectivism as opposed to individualism.
iii. Masculinity as opposed to Femininity.
v. Short-term opposed to Long-term adjustment [92,142]; REPR 84 = Encouraging informal contact amongst partners who are dispersed [143]; REPR 85 = Making it easier for partners to communicate with one another on a regular basis [144]; REPR 86 = Applying a proper requirements traceability method throughout the stages of requirements, design, and implementation [145]; REPR 87 = Identifying co-change tendencies to forecast future requirements changes and developing a corresponding policy [146,147]; REPR 88 = Utilizing altered 100 $ method for requirements prioritization [148]; REPR 89 = Considering that the client communication and requirements phase accounts for 10 to 25 percent of the overall project effort [149]; REPR 90 = Forming the groups in a manner that work overlaps so that employees are aware of the other individuals' duties [150].
The RQ1 is answered in this way.

Step 2: Sommerville and Sawyer's significant RE practices to tackle issues of SDO RE process
There is a need to study which of Sommerville & Sawyer's suggested practices are critical for addressing the RE process issues in the context of SD. 4.2.1. Identification of the significant RE practices for SDO through questionnaire survey. The S1 Appendix presents the questionnaire employed for the survey.
(a) Questionnaire format: The closed format questions ask you to rank the advantages of RE techniques for SDO on a scale of one to four. The open-ended questions are designed to find out whether respondents are using any additional RE practices except the ones listed. The questionnaire is split into two sections. The first section's goal is to gather information on the respondents' work experience, job kind, and businesses. The second section is for data collection about key RE practices based on their assessed advantages for SDO. Two rounds of pilot study were undertaken to enhance the questionnaire layout.
The following are the various types of purported benefits of RE practices [8,70]: i. High Perceived Benefits (H i ): If a RE practice is mandated and always utilized, it has a "high perceived benefit".
ii. Medium Perceived Benefits (M i ): If a RE practice is not obligatory but is commonly or often utilized, it has "medium perceived advantages".
iii. Low Perceived Benefits (L i ): If a RE practice is only employed for a few projects, it has "low perceived benefits".
iv. Zero Perceived Benefits (Z i ): If a RE practice is never or just seldom employed, it has "zero perceived benefits".
(b) Sampling and population: For acquiring a valid sample of respondents, the Convenience Sampling approach was used. Project managers, software engineers, team leaders, quality assurance managers, programmers, designers, requirements engineers, analysts, and operations managers with no less than 5 years of SDO experience are among the participants. These professionals are classified as 'developers, 'managers,' and 'senior managers,' [71].
(c) Response rate: As interested professionals have been in constant communication, 45 out of 60 answers have been received by email. The 108(T) replies were chosen for data analysis, from a total of 115 (70+45) responses, grounded on the participant's company profile, job description, and appropriate experience. Table 1 displays the results of the first questionnaire survey.
(d) Criteria for choosing significant RE practices: If at least 50% of respondents believe that a RE practice's perceived advantages fall into the 'high perceived benefits' and 'medium perceived benefits' categories, then that RE practice is considered 'significant' for resolving RE process issues for outsourced software development projects. An approach comparable to this, has been used successfully in previous investigations [70][71][72].

Survey outcomes and selecting the significant RE practices.
To determine the significant RE practices, out of the four classes of the RE practices' perceived benefits, only the RE practices belonging to 'high perceived benefits' and 'medium perceived benefits' classes have been regarded based on the definitions of perceived benefits' classes [8]. The Prominence Level (PL) for every RE practice indicates the percentage of replies in the 'high perceived benefits' and 'medium perceived benefits' classes, and is computed as specified in Eq 1: The survey's findings are reported in S2 Appendix.
The findings reveal that the bulk of the RE practices advised by Sommerville and Sawyer are significant for SDO with 43 out of 49 practices (87.76%) meeting the essential criterion. Fig  4 depicts the percentages of practices and significant practices in relation to major RE process steps.

Step 3: Identification of the additional RE practices to tackle issues of SDO RE process
Another questionnaire survey was employed for identification of the additional RE practices which are adopted by SDO professionals for addressing RE issues.

Questionnaire survey for finding additional SDO RE practices.
The S3 Appendix presents the questionnaire employed for the survey.
a. Questionnaire format: The questionnaire is split into two segments. The first segment's goal is to gather information on the participants' work experience, job kind, and businesses. The second segment is dedicated for gathering the RE practices used by SDO practitioners to handle the issues they confront. Two rounds of pilot study were undertaken to enhance the questionnaire design.
b. Sampling and population: For acquiring a valid sample of participants, the Convenience Sampling approach was used. Project managers, software engineers, team leaders, quality assurance managers, programmers, designers, requirements engineers, analysts, and operations managers with no less than 5 years of SDO experience are among the respondents.
c. Response rate: There have been a total of 110 replies. The 106 replies were chosen for data analysis from 110 responses grounded on the participant's corporate profile, job title, appropriate experience, and data reliability. Table 2 includes details about the study's second questionnaire survey. ii. Persons who take part in the business processes' pursuits.

Consolidation of SDO RE practices.
iii. As mentioned by client services, persons who are interested or effected.
iv. Client-supplied requirements or the requirements of multiple partners.
v. Challenges that stakeholders encounter.
vi. Specialists in the field.
vii. Limitations, rules, and criteria that must be adhered to in the specific domain.
viii. Existing comparable systems.
ix. Consumers of the existing comparable systems.
x. Records pertaining to the target system such as ledger books, bills, invoices, and notifications.

Exhaustive list of RE practices to tackle usually arising SDO RE process issues
To address the usually arising issues of RE process in the context of SDO, it can be seen in sections 4. As a result, there are 147(90+43+14) RE practices in the full list. Table 3 indicates the specifics.
This delivers a cumulative reply to RQ1, RQ2, and RQ3. The proportions of the total 147 RE practices acquired from different sources can be seen in Fig 5. As presented in Fig 5, 61 percent of RE practices were collected from the literature, 29 percent were Sommerville and Sawyer's significant RE practices, and 10% of RE practices were proposed by SDO industrial professionals.
S4 Appendix comprises of an extensive compilation of 147 RE practices for tackling typical SDO RE process issues.

Ranking RE practices
To rank the RE practices, for addressing RE process issues in case of SDO, requirements prioritization techniques have been employed. Several requirements prioritization techniques exist like Analytic Hierarchy Process (AHP), Numerical Assignment, Cumulative Voting or Hundred Dollar, Bubble Sort and Ranking etc. [151][152][153]. To make prioritization easy and efficient, some of the requirements prioritization techniques are combined [152,154]. For example, for Planning Game (PG), Numerical Assignment and Ranking are combined [152,154]. For this study, Numerical Assignment and Hundred Dollar techniques have been combined. In the first step, by applying. Numerical Assignment technique, RE practices have been divided into High, Medium, and Low groups [153,155] based on the importance of RE practices to address SDO RE process issues. In the second step, RE practices within each group have been ranked through Hundred Dollar technique.

Focus group sessions
To rank the RE practices, two Focus Group sessions have been conducted and each session continued for four hours. Three experts having academic and industrial experience have participated in the sessions. The details about the participants have been provided in the Table 4.

Prioritizing RE practices into High, Medium, and Low groups through Numerical Assignment technique
The RE practices having High, Medium and Low importance to address SDO RE process issues, have been presented in Tables 5-7 respectively. In High importance group there are 83 RE practices, in Medium importance group there are 41 RE practices whereas in Low importance group there are 23 RE practices.

Ranking RE practices within each group through Cumulative Voting
The ranks of the RE Practices within High, Medium, and Low groups, have been shown in Tables 5-7 respectively.

Ranking RE practices within High importance group.
For ranking of RE practices that belong to Highly important group, 4000 points or dollars have been given to each participant of the focus group sessions. After mutual discussion, the participants have unanimously awarded dollars or points to each RE practice. Based on the number of awarded dollars or points, the ranks of RE practices have been ascertained. For example, RE practice REPR 1 has been awarded 90 dollars, REPR 2 has been awarded 89 dollars and REPR 3 has been awarded 88 dollars. Therefore, ranks of REPR 1, REPR 2 and REPR 3 are 1, 2 and 3 respectively as shown in the Table 5. Total of all the awarded points or dollars is 4000. Normally, 100 dollars are considered and given to each participant or stakeholder but depending upon the number of items to be ranked, more points or dollars are also deemed. For example, Regnell et al.
[156] have considered 100,000 dollars to rank 75 items (58 features and 17 feature groups). Within Highly important group, ranks of all the 83 RE practices have been shown in Table 5.

Ranking RE practices within Medium importance group.
For ranking of RE practices that belong to Mediumly important group, 1000 points or dollars have been given to each participant of the focus group sessions. The participants have unanimously awarded dollars or  points to each RE practice. Based on the number of awarded dollars or points, the ranks of 41 RE practices have been decided that have shown in Table 6.

Ranking RE practices within Low importance group.
For ranking of RE practices that belong to Low importance group, 1000 points or dollars have been given to each participant of the focus group sessions. The participants have unanimously awarded dollars to each RE practice. Based on the number of awarded dollars, the ranks of 23 RE practices have been decided that have shown in Table 7. This answers RQ4.